1. Field of the Invention
The present invention relates to a wireless remote control and in particular to a wireless remote control for a wireless load control system for controlling the amount of power delivered to an electrical load from a source of alternating-current (AC) power. Even more particularly, the invention relates to a remote control for a radio-frequency (RF) lighting control system and its antenna.
2. Description of the Related Art
Control systems for controlling electrical loads, such as lights, motorized window treatments, and fans, are known. Such control systems often use radio-frequency (RF) transmission to provide wireless communication between the control devices of the system. One example of an RF lighting control system is disclosed in commonly-assigned U.S. Pat. No. 5,905,442, issued on May 18, 1999, entitled METHOD AND APPARATUS FOR CONTROLLING AND DETERMINING THE STATUS OF ELECTRICAL DEVICES FROM REMOTE LOCATIONS, the entire disclosure of which is hereby incorporated by reference.
The RF lighting control system of the '442 patent includes wall-mounted load control devices (e.g., dimmers), and a plurality of remote control devices (e.g., table-top and wall-mounted master controls), and car visor controls. The control devices of the RF lighting control system include RF antennas adapted to transmit and receive the RF communication signals that provide for communication between the control devices of the lighting control system. To prevent interference with other nearby RF lighting control systems located in close proximity, the control devices of the RF lighting control system stores in memory and uses an identical house code (i.e., a house address). Each of the control devices is also assigned a unique device address to allow for the transmission of the RF communication signals between specific control devices. The lighting control system also comprises signal repeaters, which help to ensure error-free communication by repeating the RF signals to ensure that every device of the system reliably receives the RF signals.
Each of the load control devices includes a user interface and an integral dimmer circuit for controlling the intensity of an attached lighting load. The user interface has a pushbutton actuator for providing on/off control of the attached lighting load and a raise/lower actuator for adjusting the intensity of the attached lighting load. The load control devices may be programmed with a preset lighting intensity that may be recalled later in response to an actuation of a button of the user interface or a received RF signal.
The table-top and wall-mounted master controls each have a plurality of buttons and are operable to transmit RF signals to the load control devices to control the intensities of the lighting loads. Each of the table-top and wall-mounted master controls may also comprise one or more visual indicators, e.g., light-emitting diodes (LEDs), for providing feedback to a user in response to a received RF signal. The car visor controls may be clipped to the visor of an automobile and include three buttons for respectively controlling the lighting loads to one of a maximum intensity, a minimum intensity (i.e., off), and a preset lighting level.
In addition, some lighting control systems may include portable hand-held RF remote controls. The remote control transmits RF energy to a load control device to control the operation of the load attached to the load control device. One requirement of such RF remote controls is that they must have a suitable omnidirectional antenna that provides good transmission characteristics. The remote control embodiment described in the prior application is a transmit only device, but it is a requirement for all such RF remote control devices, whether transmit only or having transmit and receive capabilities, that they have a reliable antenna, particularly one whose propagation and/or reception characteristics are not unduly impacted by the user's hands. Therefore, there is a need for such a remote control device that has a reliable, high performance antenna operating at RF frequencies.